In recent years, there have been a rapid increase in the number of pixels and a rapid size reduction for image pickup devices such as charge-coupled devices (CCDs) and complementary metal-oxide semiconductors (CMOSs) image sensors. Thus, high-resolution images can now be taken even using a cellular phone or a notebook personal computer. Moving and still images and the like taken with an image pickup device, that is, what is called digital images, can be stored in a card-type storage medium or hard disk drive (HDD) for compact management.
Furthermore, image reproduction apparatuses called digital photoframes or the like have started to prevail. The digital photoframe includes a slot in which a card-type storage medium is accommodated. The digital photoframe functions to sequentially display, at predetermined time intervals, a plurality of still images stored in the storage medium accommodated in the slot. The digital photoframe is utilized as a desktop accessory or the like. For example, personal computers and electronic cameras also commonly function to sequentially display a plurality of still images at predetermined intervals in the same manner as that in which the digital photoframe displays images.
Thus, various image search techniques have been proposed which can be applied to selection of still images to be displayed by a digital photoframe, from a large number of still images managed by, for example, an HDD (for example, Jpn. Pat. Appln. KOKAI Publication No. 2009-59042). According to an image handling apparatus in Jpn. Pat. Appln. KOKAI Publication No. 2009-59042, when a user specifies an image, the apparatus identifies a person in the image and searches for and presents images in which the person is shown together with another person. Thus, simply by selecting an image showing the target person, the user can extract images of a related person shown together with the target person.
Conventional image search techniques including Jpn. Pat. Appln. KOKAI Publication No. 2009-59042 described above are based on the operation of accepting input search key information on, for example, a person and detecting an image group that can be detected based directly on the search key information. Thus, for example, if a person is specified and such image search as described above is performed on, for example, images taken during travel with several persons or during a party of a large number of people, no scenery image is selected (scenery images are images showing no person) and no image of a related person is selected for whom there is no image in which the related person is shown together with the specified person.
Hence, there has been a demand for a highly intelligent image search method by which if a person is specified as search key information, not only images showing the person but also images with a predetermined connection with the person can be selected.